Table 1.

Death due to brainstem herniation in rehydration related hyponatremia.

Reference	Gender	Age (years)	Race	Activity	Na (mM)	Presentation
[1]	F	28	Equatorian	Marathon	---	Said she felt dehydrated, rubber-legged and fell to the pavement. She received rehydration. The time to brainstem herniation was not published. She lost consciousness prior to admission and died in hospital the following day.
[9,10]	M	18	Alaska native (Inuit, Yupik)	Military marksmanship training at a temperature of 1190 F (43 C).	121	Dizziness, throbbing headache and nausea. With aggressive rehydration (at one stage, 10 U.S. Quarts/9.5 liter in 90 minutes) he started to vomit. Within four hours from the first symptoms, fixed and dilated pupils were recorded. A chest X-ray showed pulmonary oedema. In intensive care he developed sepsis and disseminated intravascular coagulation and died several days later of cardiac arrest. The postmortem showed diffuse cerebral and brainstem oedema, pituitary infarction [9] and hydrocephalus [10]. (Reference 9 and 10 refer to the same patient. Dr Karen O'Brien, personal communication)
[4]	F	32	---	Marathon1	117	Details on symptoms or time course not published2. She developed nephrogenic diabetes insipidus and ws treated with fluid restriction. She died of cardiac arrest due to brainstem herniation. The autopsy confirmed brainstem herniation and showed pituitary infarction. (Dr Allen Arieff, personal communication)
Present	M	In his 30's	Caucasian	Marathon	130	Light-headedness and headaches. After rehydration he started to vomit and afterwards suffered a respiratory arrest. The CT brain scan showed midbrain herniation into the foramen magnum and severe hydrocephalus (Figure 1A&B). Formal brainstem death testing was performed 16 hours after he collapsed.

¹The authors report on 7 patients participating in several marathon runs in Texas, California and Canada between 1993 to 1999. Six patients survived, one died.

²From the 7 reported cases, the diagnosis of hyponatremic encephalopathy was suspected in 6 who were treated with intravenous NaCl. All made a full recovery [4]. The patient who died did so primarily because of mismanagement. She was treated with fluid restriction, a strategy for which there is no supporting data (Dr A Arieff, personal communication).